Neck rot is a serious fungal disease of onions, causing them to rot in store. The fungus enters the bulb during its period of growth but only causes the rot later. It is worst in wet years and in cases where the onion plants have been grown too strongly with too much manure or fertiliser. Heavy feeding also leads to ‘thick neck’ onions, which do not store well.

Destroy all rotted onions – do not simple dump them – they are a source of infection for the following year. Dress seed and sets with a dusting of Systemic Fungicide before sowing.